diff --git a/.ci/magician/cmd/request_reviewer_test.go b/.ci/magician/cmd/request_reviewer_test.go
index f40288ddb2ab..b2af19be6b2d 100644
--- a/.ci/magician/cmd/request_reviewer_test.go
+++ b/.ci/magician/cmd/request_reviewer_test.go
@@ -25,6 +25,9 @@ import (
 
 func TestExecRequestReviewer(t *testing.T) {
 	availableReviewers := github.AvailableReviewers()
+	if len(availableReviewers) < 3 {
+		t.Fatalf("not enough available reviewers (%v) to run TestExecRequestReviewer (need at least 3)", availableReviewers)
+	}
 	cases := map[string]struct {
 		pullRequest             github.PullRequest
 		requestedReviewers      []string
diff --git a/.ci/magician/github/membership.go b/.ci/magician/github/membership.go
index c627cc14624a..d3694ccd7255 100644
--- a/.ci/magician/github/membership.go
+++ b/.ci/magician/github/membership.go
@@ -24,97 +24,6 @@ import (
 	"golang.org/x/exp/maps"
 )
 
-var (
-	// This is for the random-assignee rotation.
-	reviewerRotation = map[string]struct{}{
-		"slevenick":   struct{}{},
-		"c2thorn":     struct{}{},
-		"rileykarson": struct{}{},
-		"melinath":    struct{}{},
-		"ScottSuarez": struct{}{},
-		"shuyama1":    struct{}{},
-		"SarahFrench": struct{}{},
-		"roaks3":      struct{}{},
-		"zli82016":    struct{}{},
-		"trodge":      struct{}{},
-		"hao-nan-li":  struct{}{},
-		"NickElliot":  struct{}{},
-		"BBBmau":      struct{}{},
-	}
-
-	// This is for new team members who are onboarding
-	trustedContributors = map[string]struct{}{}
-
-	// This is for reviewers who are "on vacation": will not receive new review assignments but will still receive re-requests for assigned PRs.
-	// User can specify the time zone like this, and following the example below:
-	pdtLoc, _           = time.LoadLocation("America/Los_Angeles")
-	bstLoc, _           = time.LoadLocation("Europe/London")
-	onVacationReviewers = []onVacationReviewer{
-		// Example: taking vacation from 2024-03-28 to 2024-04-02 in pdt time zone.
-		// both ends are inclusive:
-		// {
-		// 	id:        "xyz",
-		// 	startDate: newDate(2024, 3, 28, pdtLoc),
-		// 	endDate:   newDate(2024, 4, 2, pdtLoc),
-		// },
-		{
-			id:        "hao-nan-li",
-			startDate: newDate(2024, 4, 11, pdtLoc),
-			endDate:   newDate(2024, 6, 14, pdtLoc),
-		},
-		{
-			id:        "ScottSuarez",
-			startDate: newDate(2024, 4, 30, pdtLoc),
-			endDate:   newDate(2024, 7, 31, pdtLoc),
-		},
-		{
-			id:        "SarahFrench",
-			startDate: newDate(2024, 8, 2, bstLoc),
-			endDate:   newDate(2024, 8, 6, bstLoc),
-		},
-		{
-			id:        "shuyama1",
-			startDate: newDate(2024, 5, 22, pdtLoc),
-			endDate:   newDate(2024, 5, 28, pdtLoc),
-		},
-		{
-			id:        "melinath",
-			startDate: newDate(2024, 6, 26, pdtLoc),
-			endDate:   newDate(2024, 7, 22, pdtLoc),
-		},
-		{
-			id:        "slevenick",
-			startDate: newDate(2024, 7, 5, pdtLoc),
-			endDate:   newDate(2024, 7, 16, pdtLoc),
-		},
-		{
-			id:        "c2thorn",
-			startDate: newDate(2024, 7, 10, pdtLoc),
-			endDate:   newDate(2024, 7, 16, pdtLoc),
-		},
-		{
-			id:        "rileykarson",
-			startDate: newDate(2024, 7, 18, pdtLoc),
-			endDate:   newDate(2024, 8, 10, pdtLoc),
-		},
-		{
-			id:        "roaks3",
-			startDate: newDate(2024, 8, 2, pdtLoc),
-			endDate:   newDate(2024, 8, 9, pdtLoc),
-		},
-		{
-			id:        "slevenick",
-			startDate: newDate(2024, 8, 10, pdtLoc),
-			endDate:   newDate(2024, 8, 17, pdtLoc),
-		},
-		{
-			id:        "trodge",
-			startDate: newDate(2024, 8, 24, pdtLoc),
-			endDate:   newDate(2024, 9, 2, pdtLoc),
-		},
-	}
-)
-
 type UserType int64
 
 type date struct {
diff --git a/.ci/magician/github/membership_data.go b/.ci/magician/github/membership_data.go
new file mode 100644
index 000000000000..7b8f2964faee
--- /dev/null
+++ b/.ci/magician/github/membership_data.go
@@ -0,0 +1,94 @@
+package github
+
+import "time"
+
+var (
+	// This is for the random-assignee rotation.
+	reviewerRotation = map[string]struct{}{
+		"slevenick":   {},
+		"c2thorn":     {},
+		"rileykarson": {},
+		"melinath":    {},
+		"ScottSuarez": {},
+		"shuyama1":    {},
+		"SarahFrench": {},
+		"roaks3":      {},
+		"zli82016":    {},
+		"trodge":      {},
+		"hao-nan-li":  {},
+		"NickElliot":  {},
+		"BBBmau":      {},
+	}
+
+	// This is for new team members who are onboarding
+	trustedContributors = map[string]struct{}{}
+
+	// This is for reviewers who are "on vacation": will not receive new review assignments but will still receive re-requests for assigned PRs.
+	// User can specify the time zone like this, and following the example below:
+	pdtLoc, _           = time.LoadLocation("America/Los_Angeles")
+	bstLoc, _           = time.LoadLocation("Europe/London")
+	onVacationReviewers = []onVacationReviewer{
+		// Example: taking vacation from 2024-03-28 to 2024-04-02 in pdt time zone.
+		// both ends are inclusive:
+		// {
+		// 	id:        "xyz",
+		// 	startDate: newDate(2024, 3, 28, pdtLoc),
+		// 	endDate:   newDate(2024, 4, 2, pdtLoc),
+		// },
+		{
+			id:        "hao-nan-li",
+			startDate: newDate(2024, 4, 11, pdtLoc),
+			endDate:   newDate(2024, 6, 14, pdtLoc),
+		},
+		{
+			id:        "ScottSuarez",
+			startDate: newDate(2024, 4, 30, pdtLoc),
+			endDate:   newDate(2024, 7, 31, pdtLoc),
+		},
+		{
+			id:        "SarahFrench",
+			startDate: newDate(2024, 8, 2, bstLoc),
+			endDate:   newDate(2024, 8, 6, bstLoc),
+		},
+		{
+			id:        "shuyama1",
+			startDate: newDate(2024, 5, 22, pdtLoc),
+			endDate:   newDate(2024, 5, 28, pdtLoc),
+		},
+		{
+			id:        "melinath",
+			startDate: newDate(2024, 6, 26, pdtLoc),
+			endDate:   newDate(2024, 7, 22, pdtLoc),
+		},
+		{
+			id:        "slevenick",
+			startDate: newDate(2024, 7, 5, pdtLoc),
+			endDate:   newDate(2024, 7, 16, pdtLoc),
+		},
+		{
+			id:        "c2thorn",
+			startDate: newDate(2024, 7, 10, pdtLoc),
+			endDate:   newDate(2024, 7, 16, pdtLoc),
+		},
+		{
+			id:        "rileykarson",
+			startDate: newDate(2024, 7, 18, pdtLoc),
+			endDate:   newDate(2024, 8, 10, pdtLoc),
+		},
+		{
+			id:        "roaks3",
+			startDate: newDate(2024, 8, 2, pdtLoc),
+			endDate:   newDate(2024, 8, 9, pdtLoc),
+		},
+		{
+			id:        "slevenick",
+			startDate: newDate(2024, 8, 10, pdtLoc),
+			endDate:   newDate(2024, 8, 17, pdtLoc),
+		},
+		{
+			id:        "trodge",
+			startDate: newDate(2024, 8, 24, pdtLoc),
+			endDate:   newDate(2024, 9, 2, pdtLoc),
+		},
+	}
+)
diff --git a/.ci/magician/github/reviewer_assignment_test.go b/.ci/magician/github/reviewer_assignment_test.go
index ad85f5232c32..6a2cb33b6a25 100644
--- a/.ci/magician/github/reviewer_assignment_test.go
+++ b/.ci/magician/github/reviewer_assignment_test.go
@@ -24,6 +24,9 @@ import (
 )
 
 func TestChooseCoreReviewers(t *testing.T) {
+	if len(AvailableReviewers()) < 2 {
+		t.Fatalf("not enough available reviewers (%v) to test (need at least 2)", AvailableReviewers())
+	}
 	firstCoreReviewer := AvailableReviewers()[0]
 	secondCoreReviewer := AvailableReviewers()[1]
 	cases := map[string]struct {
diff --git a/.github/workflows/request-reviewer.yml b/.github/workflows/request-reviewer.yml
index 45c5ffacd4e6..7748d32f8e04 100644
--- a/.github/workflows/request-reviewer.yml
+++ b/.github/workflows/request-reviewer.yml
@@ -24,6 +24,8 @@ jobs:
     steps:
       - name: Checkout Repository
         uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.2
+        with:
+          ref: main
       - name: Set up Go
         uses: actions/setup-go@0c52d547c9bc32b1aa3301fd7a9cb496313a4491 # v5.0.0
         with: